A need exists for additional methods to prepare 3-methyl-2-nitrobenzoic acid that are selective and cost-effective. 3-Methyl-2-nitrobenzoic acid is useful as in intermediate in the preparation of agrochemicals such as Rynaxypyr® and Cyazypyr®.
Oxidation of mono-alkyl ortho-nitroalkylaromatic compounds is exemplified in Jacobsen, U.S. Pat. No. 5,591,890. Selective oxidation of one alkyl group in ortho-nitroalkylaromatic compounds with two or more alkyl groups is not disclosed in this patent.
Oxidation of 2-nitro-p-xylene is disclosed in Jacobson and Ely, Chemical Industries 1996, 68, 87-96. Selective oxidation of one alkyl group in ortho-nitroalkylaromatic compounds with two or more alkyl groups is not disclosed in this publication.
Oxidation of 2-nitro-m-xylene is disclosed in JP05132450 using H2SO4 and stoichiometric CrO3.